A Review of Classification, Causes, and Amelioration of Global Salt‐Affected Soil Based on the Meta‐Analysis

Abstract

Soil salinization poses a significant threat to sustainable global agriculture, critically impacting plant growth, soil fertility, and ecosystem stability. This paper first provides a comprehensive overview of soil salinization, including its definition, types, classifications, global distribution, historical continuity, and associated environmental impacts. Then, we examine salinization's causes, processes, and mechanisms, offering an in‐depth classification of saline, sodic, and saline‐sodic soils. Through physicochemical analysis, it characterizes the unique challenges of different types of salinized soils. A meta‐analysis of 254 global case studies demonstrates that applying soil conditioners effectively ameliorates three kinds of salt‐affected soils. Specifically, gypsum application resulted in a 13.4% reduction in pH in saline soils and a significant (p < 0.001) decrease in the exchangeable sodium percentage. Mixed conditioners reduced the exchangeable sodium percentage of sodic soils by 58.6% through synergistic effects. Biochar showed a pronounced effect in sodic soils, increasing soil organic carbon by 65.7%, with a minimal reduction in pH (4.0%). Importantly, mixed conditioners enhanced microbial biomass carbon in saline‐sodic soils by 68.8% and increased available phosphorus by 97.6%. However, gypsum application did not consistently decrease electrical conductivity (EC); in sodic soils, it led to a 21.0% increase in EC. Additionally, field experiments exhibited superior desalination performance relative to controlled laboratory conditions, with corresponding EC effect sizes of −0.26 and 0.04, respectively. Treatments exceeding 3 years in duration yielded more significant improvements than those lasting less than 3 years. Path analysis identified soil conditioner characteristics as the primary drivers of salt reduction, with the most substantial direct effect (path coefficient = −0.847, p < 0.001), surpassing the influence of environmental factors and initial soil properties. Based on these findings, the paper proposes a soil‐type‐specific remediation framework, emphasizing the functional compatibility between soil conditioner properties and soil salinity characteristics. These findings establish a soil‐type‐specific remediation framework, guiding tailored conditioner selection to enhance ecological and agricultural sustainability in salt‐affected soil reclamation.